1. Field of the Invention
The present invention relates to a wireless communication system using multiple bands. More particularly, the present invention relates to an apparatus and a method for supporting data transmission and reception of a mobile station using an asymmetric band in a wireless communication system which utilizes multiple bands.
2. Description of the Related Art
As wireless communication systems advance, service type expansion and high service quality are increasingly being demanded. As a result, a broadband wireless communication system has been introduced.
The broadband wireless communication system utilizes a limited frequency band. Accordingly, to provide broadband services, the broadband wireless communication system utilizes an available resource in the limited frequency band. For example, in a wireless communication system based on the Institute of Electrical and Electronics Engineers (IEEE) 802.16 standard, a Base Station (BS) manages at least one Frequency Assignment (FA). The BS provides the wireless communication service to a Mobile Station (MS) over its managed FA.
FIGS. 1A and 1B depict a configuration according to a number of frequency bands supported in a wireless communication system according to the related art.
FIG. 1A depicts an MS receiving a wireless communication service using one FA at a time, and FIG. 1B depicts an MS receiving the wireless communication service using two FAs at a time.
Referring to FIG. 1A, the MS 100 can migrate from an FA1 zone 120 to an FA2 zone 140. Herein, the FA1 zone 120 indicates a service coverage area using the FA1 and the FA2 zone 140 indicates a service coverage area using the FA2. For example, when the MS 100 travels in the FA1 zone 120, the MS 100 operates only one FA (e.g., FA1). When the FA1 and the FA2 are managed by different BSs, the MS 100 may use the wireless communication service using the FA2 after handover between the FAs.
Referring to FIG. 1B, it is assumed that the MS 150 can use at least two FAs. The MS 150 can receive the wireless communication service using both of the FA1 zone 160 and the FA2 zone 180. When the MS and the BS transmit and receive signals over the multiple FAs as above, the MS and the BS can transmit and receive high-capacity data at a high data rate.
When the MS uses a plurality of the FAs at the same time, the FAs used by the MS can be configured asymmetrically as shown in FIGS. 2A, 2B and 2C.
FIGS. 2A, 2B and 2C depict asymmetric frequency band configuration in a wireless communication system supporting multiple bands according to the related art.
Referring to FIG. 2A, the FA1 201 is used to transmit UpLink (UL) data, the FA2 203 is used to transmit DownLink (DL) data, and the FA3 205 is used to transmit UL data and DL data. That is, the FA1 201 and the FA2 203 indicate the FAs supporting a Frequency Division Duplex (FDD) structure, and the FA3 205 indicates the FA supporting a Time Division Duplex (TDD) structure. When the FA2 203 and the FA3 205 are allocated to the MS 150, the MS 150 has an asymmetric carrier aggregation and thus a DL signal is received using DL regions of the FA2 203 and the FA3 205 and a UL signal is transmitted using a UL region of the FA3 205.
Referring to FIG. 2B, the FA1 211, the FA2 213, and the FA3 215 are used to transmit UL data and DL data. Namely, the FA1 211, the FA2 213, and the FA3 215 indicate FAs supporting the TDD structure.
When the DL region of the FA1 211 and the FA2 213 are allocated to the MS 150, the MS 150 has the asymmetric carrier aggregation and thus a DL signal is received using the DL regions of the FA1 211 and the FA2 213 and a UL signal is received using the UL region of the FA2 213.
Referring to FIG. 2C, the FA1 221 is used to transmit DL data, the FA2 223 is used to transmit UL data and DL data, and the FA3 225 is used to transmit UL data. That is, the FA1 221 and the FA3 225 indicate FAs supporting the FDD structure, and the FA2 223 indicates an FA supporting the TDD structure.
When the FA1 221, the DL region of the FA2 223, and the FA3 225 are allocated to the MS 150, the MS has the asymmetric carrier aggregation and thus a DL signal is received using the FA1 221 and the DL region of the FA2 223 and a UL signal is received using the FA3 225.
The BS in the wireless communication system allocates a resource to the MS to provide the wireless communication service using channel feedback information received from the MS. However, in the asymmetric carrier aggregation, there can be no UL channel symmetrical to the DL channel. In this regard, what is needed is a separate method for transmitting the channel feedback information between the BS and the MS in the asymmetric carrier aggregation.